<div class="d-flex justify-content-center">
    <div class="d-flex align-items-center login-content">
    <form [formGroup]="myForm" (ngSubmit)="onSubmit(myForm.value)">
        <h3 class="d-flex justify-content-center">用户登录</h3>
        <div class="form-group">
            <label for="userName" class="">用户名</label>
            <input type="text" class="form-control" id="userName" aria-describedby="输入用户名" name="userName"
                [formControl]="userName" [ngClass]="{'is-invalid':userName.invalid, 'is-valid':userName.valid}">
            <div class="valid-feedback">
                用户名格式正确!
            </div>
            <div class="invalid-feedback">
                <span *ngIf="userName.hasError('required')">
                    用户名必须填写
                </span>
                <span>
                    用户名长度必须大于3位,小于20位
                </span>
            </div>
        </div>
        <div class="form-group">
            <label for="password">密码</label>
            <input type="password" class="form-control" id="password" name="password" [formControl]="password"
                [ngClass]="{'is-invalid':password.invalid,'is-valid':password.valid}">
            <div class="valid-feedback">
                密码填写正确!
            </div>
            <div class="invalid-feedback">
                密码必须大于6位，小于16位
            </div>
        </div>
        <button type="submit" class="btn btn-primary btn-block"  id="btnLogin">登录</button>
    </form>
</div>
</div>
